Suspension-insulator.



0. LE '0. FORTESCUE.

SUSPENSION INSULATOR.

APPLICATION FILED- MAY 25, 1914. RENEWED 'DEC. 31. 1917.

1,259,385. Patented Mar. 12, 1918.

WITNESSES: VENTOR ATTORNEY dischar es.

W ST T T N -O F E LIE a. roa'r'nscun, or rrr'rsnnnen, PENNSYLVANIA, assiendarro wns'rnm. nousnnnnc'rmc a m murnc rpnme courm, A coaronarion or rmmsyn- VANIL- Application filed Kay 25, 1914, Serial Ilo. a-mgoa To it may 6mm: 1 m

' -Be it known that I, Gimme Ln G. B onrnsctm, a subject of the King ofGreat'Bri't- Y My invention relates to insulators, and particularly to suspension-type insulators vfor supporting high-potential lines or conductors. P a When a difierenee of potential exists between adjacent conducting bodies, the a1 r .5 or other interposed insulating medium s subjected to stresses lg reason of the electric f field produced. A-' eld of this character ma be represented by means" of the lines call ed electrostatic; flow lines, thedistri- 'bution' and arrangementfoi which are de- 1 pendent upon the shapes and sizes of the conducting bodies, thenspacing, the char- 7 acter and shape of the insulating medlum' Q and the potential of the bodies.

' 6 Heretofore, suspenslomtype insulators,

' such as porcelain insulators, flexibly con- 7 nected to one anotherjand having corru gated'surfaces or otherwise so constructed as to provide very long surface distances,

80 have been bodies in order to insulate them from each other. 7 It was intended that these insulating bodies", by providing long leakage paths between the conducting bodies, would sub:

stantiallypreclude the occurrence of surface It is well known that discharges of this "nd occurwhen the air adjacent to the insulating bodies is subjected to undue-- concentrations of potential stresses which 40 may result from the incorrect shapes of conducting terminals, or from the incorrect iform of insulating bodies,

i said factors. v

- As disclosed in Patent No. 1,129,520, 46 ranted February'23, 1915,"to the Westmg- 1, fiouse' Electric and Manufacturing Comany 11' on anapplicationfiled by K. C.

3 anda S. W. F arnsworth and C. Le Fortescue', the concentration of potent al 50 stresses caused by the incorrect .form of msulating bodies may beentirely avoided by making them ofsuchshapes as to conform to the electrostatic lines of force vvhich would represent the existing electricfields between the conducting bOdlGS 1f they were l M susrmtslon-msnmron.

" Specification Letters latent.

' conductors are disposed.

interposed between conducting or from both of comprises a conducting member or electrode Patented Mania-191s. Renewed December 31,- 1917. Serial No. 209,795.

-located 'in a homogeneous insulating medium, such as air.

The concentration of otentialfstresses' caused by the incorrects a e of the conducting terminals may be su stantially pre-' eluded. by modifying the form of their adjacent and opposed surfaces, and the insulating strength of'a transmission line support I may be increased if the external electrostatic field surrounding the 'su port is .so, dis-. tributed as to insure the dlstribution of uni formsurface stresses thereupon, as disclosed 13y atent application, SerialNo. 837,7 t2, l e

ay 11, 1914. One object of my invention is to provide a suspension-t e insulator for high-voltage conductors which is adapted to utilize, to substantially its full insulating value, the air or other insulating medium in which Another. object of my invention is .to provide a suspension-typeinsulator that, for a given voltage, will be of, smaller dimensions than has heretofore-been utilized for a simi-v lar voltage, or that, for a given size, may be capableof withstanding higher voltages than suspension insulators notbuilt in accordance with my invention.

Myinvention is illustrated in the accom: panying drawing in which the single figure is a sectional view of a suspension-type insulator embodying a form of my invention. I Referring to the drawing, a high-potential conductor 1 is secured, by means of a clam 2, to a conducting member 3 which constltutes the lower member of my suspension-type insulator 4. The insulator comprises a plurality of superposed elements or condensers 5 which are flexibly connected to one anotherby any suitable means. In the -/device shown, the flexible connection between the elements 5 comprises a hook 6 and an apertured lug7 that is located on the top portion-of the. element 5. Each element 5 8 the hollow top portion 9 of which has a contracted lower end and the bottom portion 10 of which is of frusto-conical shape. A rod 11, having an enlarged end 12, projects into the electrodes 8 and is so disposed that its enlarged end 12 is surrounded by the top portion 9. Insulating material 13 is inter osed between the said rods and the electro cs8 and serves to insulate the rod 1 from the electrode and also to hold the rod'1=10 firmly position. The exposed surface 1 L of the insulating body is of such shape as to of the exposed surface of the insulating body 18 permits the air to be utilized to its full insulating value and, therefore, greatly increases the break-down potential i between the electrodes 8. l

My invention comprises a system of con-" densers connected in series. relation to enhance I, the insulating properties of which, it is highly desirable to obtain uniform divisions of potential difference between the elements 5. c In order to increase the insulation strength of my insulator, the external electrostatic field surrounding the, same should be so distributed as to insure a substantially uniform surfaoe'distribution of a the electrostatic stresses imposed thereupon. For this purpose, I have provided an upper conducting member 15 having a conducting extension 16 of discoidal shapeandadower' conducting member 13 having a conducting extension 18 of discoidal shape.

It is desirable, for maximum efiiciency, and in order that my improved insulator may be of minimum length, that the external electrostatic field be substantially uniform and agree with the division of potene tial'between the individual elements 5 comprised in the structure t. The electrodes 16 and 18 are provided to approximate the reinsulator as to effect exdctly uniform division of the potential difference between the 7 ,various elements comprising the support.

If each or" the elements ,5 assumes its proper share of the potential difference between the .7

conductor land the supporting structureor tower (not shown), and a substantially uniform distribution of'the electrostatic field surrounding the insulator 4 is obtained, the

insulator has a very high insulating value. 75

@f course, with this approximation, the maximum efiiciency is not obtained.

In the structureshown, the lower extension 18 is charged to the potential of the conductor 1 by bein electricall thereto by means oi the metallic clamp 2. The upper extension 16. assumes a low potential by reason of its being connected, by means ofa hook 19, to the supporting structure or tower (not shown). flared lower portions 10 of the electrodes 8 extend beyond the insulating bodies 13 and thereby shield them from rain, dust, etc. As in all suspension ty e insulators, it is desirable to have flexib e connecting means 90 between the variousinsulating elements, and

I haveshown such flexible connecting means. .1 n-

It will be 'understoodrthat. various mechanisms and devices may be utilized for fl iblyconnecting the elements 5'to one an-v 95 other, and I do not. claim the specific form of flexible connecting means shown and described. s r 3 Although I have shown and described de connected The conically s5 sult which would be obtained by bounding modifications may be "effected therein within the insulating support 4 by infinite parallel the spirit and scope of my invention, and I conducting planes perpendicular to the axis desire that only such limitations shallbe imof the insulator. As above mentioned, this 'posed as are indicated in the appended 40 will effect a substantially uniform distribu claims. 10

tion of the electrostatic field external to, and I claim as my invention: '1 I m surrounding, the insulator 4.. The condi-. 1. In an insulating structure, a plurality tion for uniform distribution of potential of superposed conducting memberscompris-I among the elements 5 'is that the fluxes leaving hollow top .ortions having contracted ing t e electrodes 8 shall beof like value; lower ends "and this means that the capacitance of each laterally from said ends, rods having enelectrode 8'to ground must be inversely as *larged ends respectively surrounded b the its potential, and that the capacitance besaid top portions and having their lbwer tween adjacent pairs of electrodes must be ends attached to the top portions of the aduniform. This is approximated very-closely jacent conducting members, and bodies of 115 if the-"parallel plane surfaces or the flux disinsulating material interposed between said tributlng surfaces of the upper or lbw-fpomembers and said rods and having recesses tential electrode 15 and the lower or highto receive the top portions of the adjacent potential electrode 3 coincide with, or lie in conducting members, the exposed portions of the planes of, the lower edges ofthe elec-. ,saidinsulating bodies bein trodes 16 and 18, respectivel An insulastantially conform to the "es of force of a tor made according to the a ove plan coni the electric fields existing between the adjaforms to the law of uniform fields, and is incent conducting arts. r I sured against concentrations of electrostatic 2. In ,an insu ating structure, a plurality stresses upon its surfaces. Again, if the diof superposed conducting members compris-, 125 m'ensions of the insulating structure are 'ing hollow topv portions having contracted doubled, the ability of the insulator to resist lower ends and bottom portions extending high potentials is doubled. u laterally from said ends, rods having en- V It is unnecessary, in order to obtain good largedf ends respectively surrounded b the results, however, to so design the suspension sai bop portions and having their ower 180 -vices of specific structural details, many '100 ottom portions extending 110.

shaped, to subends flexibly secured to the top portions of the next Succeeding conducting members,- and bodies of insulating material interposed between said members and'saidrods, the exposed portions of said insulating bodies being shaped to substantially conform to the lines of force of the electric field existing between the adj acent conducting parts, the conducting members extending laterally beyond the insulating bodies. 1

3. In an insulatlng structure, a plurality of superposed conducting members comprising hollow top portions having contracted lower ends and bottom portions extending.

laterally from said ends, extensions for the top and bottom conducting members that extend laterallybeyond the intermediate conducting members, rods having enlarged ends respectively surrounded by the top portions of'the said members and having their lower ends flexibly secured to the top vportions of the next succeeding conducting members,.and

bodies of insulating material interposed between said members and said rods, the exposed portions of said insulating bodies be ing shaped'to substantially conform to the linesof force of the'electric field existing between the adjacent conducting parts.

4:. In an insulating structure, a plurality of superposed conducting members comprising hollow top portions having contracted lower ends and bottom portions extending laterally from said ends, extensions for the top and bottom conducting members that extendlaterally beyond the intermediate" conducting members, rods having enlarged ends respectively surrounded by the topportions of the said members and having their lower ends attached to the top portions of the next succeeding conducting members, and bodies of insulating material interposed between said members and said rods, the exposed portions of said insulating bodies being' shaped to substantially conform to the lines of force of the electric field existing between adjacent conducting parts, the conducting- P members extending laterally beyond the inj sulating bodies.

5. In an insulating structure, a plurality of superposed conducting'members comprlsing hollow top portions havlng contracted lower ends and bottom portions extending laterally from said ends, apertured lugs pro- I vided on the top portions, .rods having enlarged ends respectively surrounded by said, I "top portions, and hooksat their other ends respectively engagingthe said lugs, and bodies of insulating material interposed between said 'members and saidrods, the ex- 4 posed portions of said insulatin bodies being shaped to substantially on orm to the lines of force.

6. In an insulating structure, a' plurality of superposed elements each comprising a conducting member having a conically flared bottom portion, a rod projecting thereinto,

and bodies of insulating material interposed rods, and flexible connecting-means between the said elements, the top and bottom con-' ducting members having extensions that between said conducting members and said project laterally beyond the intermediate arallel surfaces coincide with th pla of the edges'of said upper and lower conduct-, ing members in order to obtain a 'substantially uniform distribution of potential difference between the conducting members.

8. In an insulating structure, a: plurality of superposed elements each comprising a conduct-ing member having a conically flared lower portion, a rod' projecting thereinto, andinsulating bodies interposed between said conducting members and said rods, theexposed surfaces of the insulatin bodiesbeing shaped to substantially con orm to the lines of force of the electric field existing between adjacent conducting members, and flexible connecting means between the said elements, the upper and the lower conducting members having portions; of discoidal shape that extendin planes that are coincident with the planes of the edges of said upper and said lower conducting members in order to obtain a substantlally uniform v,

division of potential difi'erence between the conducting members.

In testimony whereof, I have hereunto subscribed my name this 21st day of May, 1914c; T

CHARLES LE FQRTESCUE.

Witnesses: '7

GOLDIE E. MCGEE, B, B. I-Imns. 

